JOINT CELL ISOLATION CORE ABSTRACT The Joint Cell Isolation (JCI) Core of the Microenvironment in Arthritis Resource Center (MARC) will facilitate research in the San Diego community focused on the biology of the joint at the tissue and single cell level. The JCI Core will serve as a local resource for technologies such as laser capture microdissection (LCM) and flow sorting from joint tissues. No other shared resource in the San Diego area offers this type of expertise or service. The JCI Core will be led and managed by faculty and staff with extensive experience in the application of these technologies to research on rheumatologic diseases. The Core will provide a series of operator- assisted services for LCM, tissue disaggregation, and flow sorting from human and mouse joint tissues. The Core will also help with experimental design, collaborate with investigators to tailor protocols to the needs of the individual researcher, and engage in its own internal research to develop new cutting-edge methodologies for investigation into the joint microenvironment. The Aims of this Core are 1) to assist investigators in the design of experiments to isolate tissue fragments and/or single cells from human or mouse joints, 2) to assist investigators in the execution of experiments involving isolation of cells in situ from joint tissue histologic sections via LCM, and 3) to assist investigators in the execution of experiments involving disaggregation of joint tissue and sorting of specific cellular populations. The Core will also facilitate interactions with other shared resources to help investigators with needs related to the workflow for these experiments, such as procurement of synovium or cartilage samples, histological preparation of tissues, and obtaining samples that can be analyzed by transcriptomics or other technologies like chromatin accessibility. By providing services and expertise, the MARC JCI Core will enable researchers in the local community to use techniques previously unavailable to them and will add a new dimension to their research programs.